1. Field of the Invention
The invention relates to the field of analyzers used in haematology, in which blood samples are automatically analyzed, and it relates more particularly to a new device for transferring said samples, contained in closed receptacles and previously grouped together in cassettes, to the analyzer.
2. Description of the Related Art
It is known that, in order to analyze blood samples contained in sealed test tubes, it is necessary to move the test tubes to the analyzer, to agitate them to mix the blood, and then to pierce the bungs that close them in order to sample and transfer a small quantity of product to the analyzer. In order to avoid successive manipulations as much as possible, attempts have been made to automate all these operations. There is known, in particular, an automated process that consists in displacing cassettes of tubes of samples, with the help of a transport member, between an analyzer input area and an analyzer output area, a bung piercing station being provided between the two. For this purpose, the cassettes are received, one by one, on a combined pivoting table and conveyor belt. The table and conveyor belt unit pivots several times about its longitudinal axis so that the test tubes describe half-circles and their bungs move successively from a top position to a bottom position, this operation being continued until the sampled material is thoroughly mixed. Then, the transport member is halted for sufficient time to be able to carry out the piercing of the bungs and then feed the analyzer. This process, as described in EP-A-0159347, and the apparatus for implementing it, which forms a fully integrated and automated system containing a haematology type analyzer, do, however, have a certain number of drawbacks which are inherent in their design. For instance, in an input compartment of the apparatus, it is necessary, as a preliminary measure, to stack the cassettes filled with closed tubes of samples, one by one, manually. Furthermore, a lowering mechanism has to extract a cassette from the stack before it is taken over by the transport means, of the transfer belt type, in order to undergo subsequent agitation and displacement. This agitation, which is the result of inverting and not of complete rotation, has to be repeated several times, which delays the subsequent sampling operations. The pivoting table thus ensures the rearward tipping of the cassette before coming to a halt so that a first tube of sample can be partially moved out of a rack in order for a sample to be taken using a suction probe which has pierced the bung. This arrangement thus combines a number of mechanisms that do not permit sustained processing rates, or further sampling of a tube from which a sample has previously been taken.